The heart stone. The victorian dress rental plase. The historical Western house. Nanoho, and Chitori's class must be at the same plase that Akko confessed to Mariko in Girlfriends
I thought it was in Negima too, but I think I might be wrong! I wonder if the girlfriends connection is a coincidence or intentional. I don't think there are any direct references with panels or staging or the like, but the confessions might say otherwise
School groups tend to visit the same places. If you ever go to Japan and visit any famous tourist place at the time when school groups are out, you will find a LOT of them. I just returned from a trip to Japan and I saw them in Dotonbori, at Hiroshima castle, on Miyajima, basically at all the well known places. I have never been to Nagasaki but I am sure if I went I would see school groups at exactly this place.
I think it's an easy sell? They could go to Kyoto and do the shrine next to Kiyomizu-dera (which I'm pretty sure has shown up in some anime and manga), but I guess Nagasaki is becoming more in? Kyoto is so badly overtouristed now... In any case, having a romantic spot on a school trip is a trope, and realistically it's actually very common for many schools to go to the same spots.